Deterring information copying including deterrence of currency counterfeiting

ABSTRACT

A method for deterring information copying, includes: combining a watermark serial number incorporate in a given medium with a content serial number to create a combined serial number, the watermark serial number uniquely identifies the given medium, and the content serial number uniquely identifies a content stored on the given medium; creating a digital signature by encoding the combined serial number using a private key of a public/private key pair; imprinting the content serial number and the digital signature on the given medium; decoding the digital signature imprinted on the given medium using a public key of the public/private key pair to obtain the combined serial number; comparing the decoded combined serial number with the watermark serial number and the content serial number imprinted of the given medium; and in response to determining that both match the combined serial number, determining that the content is authentic.

BACKGROUND

Currency notes are printed with carefully designed measures to detercounterfeiting. Special paper is used with watermarks and inscribedsecurity threads that have printed information. The information printedfor the currency is carefully chosen, often also having miniatureprintings not easily visible to the naked eye to make reproduction moredifficult. Despite these efforts, governments still battle with asignificant percentage of counterfeited currency notes.

Currently, governments attempt to deter counterfeiting by limiting theavailability of the technologies required to counterfeit the currencies.However, sophisticated organizations have the money and power topurchase the latest counterfeiting technology, including the ability tobuy the same paper and the same printer used by the governments toproduce the currency notes. As a result, the counterfeit currencymatches the authentic currency, such that even banks cannot distinguishthem.

The prevention of unauthorized copying of copyrighted information, suchas software, movies, music, and other such media content, faces similarchallenges, with sophisticated organizations being able to purchase thetechnology to illegally copy such copyrighted information withprecision.

SUMMARY

According to one embodiment of the present invention, a method fordeterring information copying, comprises: combining a watermark serialnumber comprised in a given medium of a plurality of media with acontent serial number to create a combined serial number, wherein thewatermark serial number uniquely identifies the given medium, whereinthe content serial number uniquely identifies a content stored on thegiven medium; creating a digital signature by encoding the combinedserial number using a private key of a public/private key pair; andimprinting the content serial number and the digital signature on thegiven medium.

In one aspect of the present invention, the method further comprises:decoding the digital signature imprinted on the given medium using apublic key of the public/private key pair to obtain the combined serialnumber; comparing the decoded combined serial number with the watermarkserial number comprised in the given medium and the content serialnumber imprinted on the given medium; and in response to determiningthat the watermark serial number comprised in the given medium and thecontent serial number imprinted on the given medium match the combinedserial number, determining that the content is authentic.

In another aspect of the present invention, the method furthercomprises: in response to determining that the watermark serial numbercomprised in the given medium, or the content serial number imprinted onthe given medium, fails to match the decoded combined serial number,determining that the content is counterfeit.

In another aspect of the present invention, the given medium comprises agiven piece of financial instrument paper of a plurality of financialinstrument papers, and the content comprises printed matter printed onthe given piece of financial instrument paper, wherein the methodcomprises: combining a watermark serial number comprised in the givenpiece of financial instrument paper with a printed matter serial numberto create the combined serial number, wherein the watermark serialnumber comprised in the given piece of financial instrument paperuniquely identifies the given piece of financial instrument paper,wherein the printed matter serial number uniquely identifies the printedmatter; creating the digital signature by encoding the combined serialnumber using the private key of the public/private key pair; andprinting the printed matter serial number and the digital signature onthe given piece of financial instrument paper to create a financialinstrument.

In another aspect of the present invention, wherein the printing theprinted matter serial number and the digital signature on the givenpiece of financial instrument paper, comprises: converting the digitalsignature to a bar code; and printing the printed matter serial numberand the bar code on the given piece of financial instrument paper tocreate the financial instrument.

In another aspect of the present invention, the method furthercomprises: decoding the digital signature printed on the given piece offinancial instrument paper using a public key of the public/private keypair to obtain the combined serial number; comparing the decodedcombined serial number with the watermark serial number comprised in thegiven piece of financial instrument paper and the printed matter serialnumber printed on the given piece of financial instrument paper; inresponse to determining that the watermark serial number comprised inthe given piece of financial instrument paper and the printed matterserial number printed on the given piece of financial instrument papermatch the combined serial number, determining that the financialinstrument is authentic.

In another aspect of the present invention, wherein the given mediumcomprises a given digital content storage of a plurality of digitalcontent storages, wherein the content comprises digital content storedon the given digital content storage, wherein the method comprises:combining a watermark serial number comprised in the given digitalcontent storage with a digital content serial number to create thecombined serial number, wherein the watermark serial number uniquelyidentifies the given digital content storage, wherein the digitalcontent serial number uniquely identifies the digital content; creatingthe digital signature by encoding the combined serial number using theprivate key of the public/private key pair; and imprinting the digitalcontent serial number and the digital signature on the given digitalcontent storage.

In another aspect of the present invention, the method furthercomprises: decoding the digital signature imprinting on the givendigital content storage using a public key of the public/private keypair to obtain the combined serial number; comparing the decodedcombined serial number with the watermark serial number comprised in thegiven digital content storage and the digital content serial numberimprinted on the given digital content storage; in response todetermining that the watermark serial number comprised in the givendigital content storage and the digital content serial number imprintedon the given digital content storage match the combined serial number,determining that the digital content stored on the given digital contentstorage is an authentic copy.

System and computer program products corresponding to theabove-summarized methods are also described and claimed herein.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 illustrates an embodiment of a system for deterring informationcopying according to the present invention.

FIG. 2 is a flowchart illustrating an embodiment for encodingauthentication information in a method for deterring information copyingaccording to the present invention.

FIG. 3 illustrates an example currency note comprising the encodedauthentication information according to the embodiment of the method fordeterring information copying of the present invention.

FIG. 4 is a flowchart illustrating an embodiment for decodingauthentication information in a method for deterring information copyingaccording to the present invention.

FIG. 5 is a flowchart illustrating an embodiment for encodingauthentication information in a method for deterring digital contentcopying according to the present invention.

FIG. 6 is a flowchart illustrating an embodiment for decodingauthentication information in a method for deterring digital contentaccording to the present invention.

DETAILED DESCRIPTION

As will be appreciated by one skilled in the art, aspects of the presentinvention may be embodied as a system, method or computer programproduct. Accordingly, aspects of the present invention may take the formof an entirely hardware embodiment, an entirely software embodiment(including firmware, resident software, micro-code, etc.) or anembodiment combining software and hardware aspects that may allgenerally be referred to herein as a “circuit,” “module” or “system.”Furthermore, aspects of the present invention may take the form of acomputer program product embodied in one or more computer readablemedium(s) having computer readable program code embodied thereon.

Any combination of one or more computer readable medium(s) may beutilized. The computer readable medium may be a computer readable signalmedium or a computer readable storage medium. A computer readablestorage medium may be, for example, but not limited to, an electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system,apparatus, or device, or any suitable combination of the foregoing. Morespecific examples (a non-exhaustive list) of the computer readablestorage medium would include the following: an electrical connectionhaving one or more wires, a portable computer diskette, a hard disk, arandom access memory (RAM), a read-only memory (ROM), an erasableprogrammable read-only memory (EPROM or Flash memory), an optical fiber,a portable compact disc read-only memory (CD-ROM), an optical storagedevice, a magnetic storage device, or any suitable combination of theforegoing. In the context of this document, a computer readable storagemedium may be any tangible medium that can contain, or store a programfor use by or in connection with an instruction execution system,apparatus, or device.

A computer readable signal medium may include a propagated data signalwith computer readable program code embodied therein, for example, inbaseband or as part of a carrier wave. Such a propagated signal may takeany of a variety of forms, including, but not limited to,electro-magnetic, optical, or any suitable combination thereof. Acomputer readable signal medium may be any computer readable medium thatis not a computer readable storage medium and that can communicate,propagate, or transport a program for use by or in connection with aninstruction execution system, apparatus, or device.

Program code embodied on a computer readable medium may be transmittedusing any appropriate medium, including but not limited to wireless,wireline, optical fiber cable, RF, etc., or any suitable combination ofthe foregoing.

Computer program code for carrying out operations for aspects of thepresent invention may be written in any combination of one or moreprogramming languages, including an object oriented programming languagesuch as Java® (Java, and all Java-based trademarks and logos aretrademarks of Sun Microsystems, Inc. in the United States, othercountries, or both), Smalltalk, C++ or the like and conventionalprocedural programming languages, such as the “C” programming languageor similar programming languages. The program code may execute entirelyon the user's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's computerthrough any type of network, including a local area network (LAN) or awide area network (WAN), or the connection may be made to an externalcomputer (for example, through the Internet using an Internet ServiceProvider).

Aspects of the present invention are described below with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems) and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer program instructions. These computer program instructions maybe provided to a processor of a general purpose computer special purposecomputer or other programmable data processing apparatus to produce amachine, such that the instructions, which execute via the processor ofthe computer or other programmable data processing apparatus, createmeans for implementing the functions/acts specified in the flowchartand/or block diagram block or blocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer other programmable dataprocessing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, or other devices to causea series of operational steps to be performed on the computer, otherprogrammable apparatus or other devices to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof code, which comprises one or more executable instructions forimplementing the specified local function(s). It should also be notedthat, in some alternative implementations, the functions noted in theblock may occur out of the order noted in the figures. For example, twoblocks shown in succession may, in fact, be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved. It will also be notedthat each block of the block diagrams and/or flowchart illustration, andcombinations of blocks in the block diagrams and/or flowchartillustration, can be implemented by special purpose hardware-basedsystems that perform the specified functions or acts, or combinations ofspecial purpose hardware and computer instructions.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present invention has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the invention. Theembodiment was chosen and described in order to best explain theprinciples of the invention and the practical application, and to enableothers of ordinary skill in the art to understand the invention forvarious embodiments with various modifications as are suited to theparticular use contemplated.

FIG. 1 illustrates an embodiment of a system for deterring informationcopying according to the present invention. In this embodiment, thesystem deters the counterfeiting of printed financial instruments. Thesystem comprises financial instrument paper manufacturers 101, aprinting device 102, an encoding device 103, and an authenticationdevice 110. The financial instrument paper manufacturers 101 supply aplurality of financial instrument papers 107. Each financial instrumentpaper is used to produce one financial instrument. In this embodiment,each financial instrument paper is manufactured to comprise a uniqueserial number incorporated within the paper as a watermark. The printingdevice 102 prints the financial instruments 108 using the financialinstrument papers according to the various embodiments of the presentinvention. The encoding device 103 is operationally coupled to aprocessor 104 and a computer readable medium 105. The computer readablemedium 105 stores computer readable program code 106 and a private key109 of a public/private key pair for implementing an encoding method ofthe present invention. The authentication device 110 is operationallycoupled to a processor 111 and a computer readable medium 112. Thecomputer readable medium 112 stores computer readable program code 113and a public key 114 of the public/private key pair for implementing adecoding method of the present invention.

FIG. 2 is a flowchart illustrating an embodiment for encodingauthentication information in a method for deterring information copyingaccording to the present invention. For each financial instrument 108 tobe printed, a given piece of financial instrument paper 107 is used. Thegiven financial instrument paper 107 comprises a unique watermark serialnumber incorporated within the paper, which uniquely identifies thegiven financial instrument paper 107. The financial instrument 108 isalso assigned a printed matter serial number that is to be printed ontothe given piece of financial instrument paper 107, which uniquelyidentifies the financial instrument 108. The encoding device 103combines the watermark serial number of the given piece of financialinstrument paper 107 and the printed matter serial number to create acombined serial number (201). The encoding device 103 creates a digitalsignature by encoding the combined serial number using the private key109 of the public/private key pair (202). The printed matter serialnumber and the digital signature are printed on the given piece offinancial instrument paper 107 by the printing device 102 (203).

For example, the financial instrument 108 may comprise a currency note.FIG. 3 illustrates an example currency note comprising the encodedauthentication information according to the embodiment of the method fordeterring information copying of the present invention. The examplecurrency note paper comprises a watermark serial number 303 of ‘97468’incorporated within the paper. The watermark serial number 303 uniquelyidentifies this particular piece of currency note paper. A printedmatter serial number 302 of ‘14NH 7568998’ is assigned to the currencynote 301. Referring to both FIGS. 2 and 3, the encoding device 103combines the watermark serial number 303 and the printed matter serialnumber 302 to create a combined serial number (201). The encoding device103 creates a digital signature 304 by encoding the combined serialnumber using the private key 109 (202). Here, the encoding device 103further converts the digital signature 304 into a one-dimensional barcode. The digital signature 304 may also be converted to other forms,such as two-dimensional bar codes, without departing from the spirit andscope of the present invention. The printed matter serial number 302 andthe digital signature 304 are printed onto the particular piece ofcurrency note paper by the printing device 102 (203).

FIG. 4 is a flowchart illustrating an embodiment for decodingauthentication information in a method for deterring information copyingaccording to the present invention. To determine the authenticity of afinancial instrument, the digital signature printed on the financialinstrument 108 is read by the authentication device 110. Theauthentication device 110 decodes the digital signature using the publickey 114 of the public/private key pair to obtain the unique combinedserial number of the currency note 108 (401). As is known in the art,only a digital signature encoded with the matching private key 109 canbe correctly decoded using the public key 114. As explained above, thecombined serial number was created by combining the watermark serialnumber and the printed matter serial number of the currency note 108.The authentication device 110 compares the decoded combined serialnumber with the watermark serial number comprised in the piece offinancial instrument paper and the printed matter serial number printedon the financial instrument 108 (402). In response to determining thatboth match (403) the decoded combined serial number, the financialinstrument is determined to be authentic (404). In response todetermining that either the watermark serial number or the printedmatter serial number fails to match the decoded combined serial number,the financial instrument is determined to be counterfeit (405).

For example, with reference to the example currency note illustrated inFIG. 3, the authentication device 110 reads the digital signature 304printed on the currency note 301 and decodes the digital signature 304using the public key 114 to obtain the combined serial number (401). Theauthentication device 110 compares the decoded combined serial numberwith the watermark serial number 303 comprised in the piece of currencynote paper and the printed matter serial number 302 printed on thecurrency note 301 (402). In response to determining that both thewatermark serial number 303 and the printed matter serial number 302match the decoded combined serial number, the currency note 301 isdetermined to the authentic (404). In response to determining thateither the watermark serial number 303 or the printed matter serialnumber 302 fails to match the decoded combined serial number, thecurrency note 301 is determined to be counterfeit (405).

With the present invention, the currency note 301 has three uniqueidentifiers: the watermark serial number 303, which uniquely identifiesthe particular piece of currency note paper; the printed matter serialnumber 302, which uniquely identifies the currency note 301; and thedigital signature 304, which uniquely associates the watermark serialnumber 303 and the printed matter serial number 302 through use of theprivate key 109. Requiring each piece of currency note paper to comprisea unique watermark serial number increases the difficulty in reproducingthe paper for counterfeiting purposes, as this requires the cooperationof the currency note paper manufacturers. Further, this requirementprevents the reproduction of a known printed matter serial number asthis is insufficient to create an association with the unique watermarkserial number for each currency note. Even if both a unique watermarkedserial number and a unique printed matter serial number are produced,the digital signature for confirming their unique association cannot becreated without access to the private key 109. Use of the private key109 also deters introduction of new printed matter serial numbers incounterfeit currency. With an improperly introduced printed matterserial number, the digital signature for confirming its uniqueassociation with the unique watermark serial number cannot be createdwithout access to the private key 109. Thus, using the combination ofthe three unique identifiers on each currency note deters thecounterfeiting of paper currencies.

Although the embodiments of the present invention is described above inthe context of currency notes, the present invention may also be used todeter the copying of other types of printed financial instrumentswithout departing from the spirit and scope of the present invention.Other printed financial instruments may include, but are not limited to,bank checks, bank deposit certificates, bond certificates, bank loans,commercial papers, agreements, stamp papers, band drafts, sharescertificates, demand drafts, treasury bonds, high value instruments,bills of exchange, future and option contracts, debt instruments, equityinstruments, bearer bonds, bonds issued by governments, certificates ofdeposit, and lottery bonds. The three unique identifiers may be usedwith these financial instruments, as well as with other printed matterthat requires uniqueness. For example, referring to FIGS. 2 and 4, inthe bank check example, a piece of bank check paper is manufactured witha watermark serial number that uniquely identifies that piece of bankcheck paper. A check serial number is assigned to the bank check touniquely identify the bank check. An example of a unique check serialnumber may include a combination of the account number, bank identifier,and check number. The encoding device 103 combines the watermark serialnumber of the piece of bank check paper and the check serial number tocreate the combined serial number (201). The encoding device 103 createsa digital signature by encoding the combined serial number using theprivate key 109 of the public/private key pair (202). The digitalsignature creates a unique association between the watermark serialnumber of the piece of bank check paper and the bank check serialnumber. The bank check serial number and the digital signature areprinted on the piece of bank check paper (203).

To determine the authenticity of the bank check, the decoding device 110reads the digital signature printed on the bank check and decodes thedigital signature using the public key 114 of the public/private keypair to obtain the combined serial number (401). The decoding device 110compares the decoded combined serial number with the watermark serialnumber comprised in the piece of bank check paper and the check serialnumber printed on the bank check (402). In response to determining thatboth match (403), the bank check is determined to be authentic (404). Inresponse to determining that either the watermark serial number or thecheck serial number fails to match, the bank check is determined to becounterfeit (405).

The present invention may also be applied to media other than paper todeter the copying of information. For example, the present invention maybe used with a digital content storage for storing digital contentprotected by copyright, such as software, movies, music, or images. Thedigital content storage may include the same forms as the computerreadable medium defined above. FIG. 5 is a flowchart illustrating anembodiment for encoding authentication information in a method fordeterring digital content copying according to the present invention. Agiven digital content storage of a plurality of digital content storagescomprises a watermark serial number incorporated within the givendigital content storage, which uniquely identifies the given digitalcontent storage. The digital content stored in the given digital contentstorage is also assigned a digital content serial number to uniquelyidentify the digital content. The encoding device 103 combines thewatermark serial number of the given digital content storage and uniquedigital content serial number to create a combined serial number (501).The encoding device 103 creates a digital signature by encoding thecombined serial number using the private key 109 of the public/privatekey pair (502). The digital content serial number and the digitalsignature are imprinted onto the given digital content storage by anappropriate imprinting device (503).

FIG. 6 is a flowchart illustrating an embodiment for decodingauthentication information in a method for deterring digital contentaccording to the present invention. To determine the authenticity ofdigital content stored on a digital content storage, the digitalsignature imprinted on the given digital content storage is read by theauthentication device 110. The authentication device 110 decodes thedigital signature using the public key 114 of the public/private keypair to obtain the combined serial number (601). As explained above, thecombined serial number was created by combining the watermark serialnumber and the digital content serial number of the given digitalcontent storage. The authentication device 110 compares the decodedcombined serial number with the watermark serial number comprised in thegiven digital content storage and the digital content serial numberimprinted on the given digital content storage (602). In response todetermining that both match the decoded combined serial number (603),the digital content stored on the given digital content storage isdetermined to be an authentic copy (604). In response to determiningthat either the watermark serial number or the imprinted digital contentnumber fails to match (603), the digital content stored on the givendigital content storage is determined to be a counterfeit copy (605).

For example, assume that the computer readable medium comprises a givencompact disc (CD). The CD is manufactured to comprise a watermark serialnumber incorporated within the CD that uniquely identifies thisparticular CD. A digital content serial number is assigned to thedigital content stored on the given CD. The encoding device 103 combinesthe watermark serial number comprised in the given CD and the digitalcontent serial number to create a combined serial number (501). Theencoding device 103 creates a digital signature by encoding the combinedserial number using a private key 109 of the public/private key pair(502). The digital signature and the digital content serial number areimprinted onto the given CD (503).

To determine the authenticity of the given CD, the authentication device110 reads the digital signature imprinted on the given CD and decodesthe digital signature using the public key 114 of the public/private keypair to obtain the combined serial number (601). The authenticationdevice 110 compares the decoded combined serial number with thewatermark serial number incorporated within the given CD and the digitalcontent serial number imprinted on the given CD (602). In response todetermining that both match (603), the digital content stored on thegiven CD is determined to be an authentic copy (604). In response todetermining that either the watermark serial number incorporated withinthe given CD or the digital content serial number imprinted on the givenCD fails to match, the digital content stored on the given CD isdetermined to be a counterfeit copy (605).

The descriptions of the various embodiments of the present invention hasbeen presented for purposes of illustration, but are not intended to beexhaustive or limited to the embodiments disclosed. Many modificationsand variations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

What is claimed is:
 1. A system, comprising: a plurality of securityinstrument media, each security instrument medium of the plurality ofsecurity instrument media used to produce a security instrument; anencoding device comprising: a processor; and a computer readable storagemedium having computer readable program code embodied in the computerreadable storage medium, wherein when the computer readable program codeis executed by the processor, the encoding device configured to: markonto each security instrument medium of the plurality of securityinstrument media a unique matter serial number, wherein each securityinstrument medium is associated with a unique watermark serial numberincorporated within the security instrument medium as a watermark,wherein each unique watermark serial number uniquely identifies thesecurity instrument medium of a given security instrument within whichthe unique watermark serial number is incorporated, wherein each uniquematter serial number uniquely identifies the given security instrumentcreated from the security instrument medium onto which the unique matterserial number is marked; for the given security instrument, combine theunique watermark serial number incorporated within the securityinstrument medium of the given security instrument and the unique matterserial number marked onto the security instrument medium of the givensecurity instrument to create a unique combined serial number; create adigital signature by encoding the unique combined serial number using aprivate key of a public/private key pair; and an imprinting device,wherein the imprinting device is configured to imprint the digitalsignature on the security instrument medium of the given securityinstrument.
 2. The system of claim 1, wherein the encoding device isfurther configured to: convert the digital signature to a bar code,wherein the imprinting device further prints the bar code onto thesecurity instrument medium of the given security instrument.
 3. Asystem, comprising: a plurality of security instrument media, eachsecurity instrument medium of the plurality of security instrument mediaused to produce a security instrument; an encoding device comprising: afirst processor; and a first computer readable storage medium havingcomputer readable program code embodied in the first computer readablestorage medium, wherein when the first computer readable program code isexecuted by the first processor, the encoding device configured to: markonto each security instrument medium of the plurality of securityinstrument media a unique matter serial number, wherein each securityinstrument medium is associated with a unique watermark serial numberincorporated within the security instrument medium as a watermark,wherein each unique watermark serial number uniquely identifies thesecurity instrument medium of a given security instrument within whichthe unique watermark serial number is incorporated, wherein each uniquematter serial number uniquely identifies the given security instrumentcreated from the security instrument medium onto which the unique matterserial number is marked; for the given security instrument, combine theunique watermark serial number incorporated within the securityinstrument medium of the given security instrument and the unique matterserial number marked onto the security instrument medium of the givensecurity instrument to create a unique combined serial number; create adigital signature by encoding the unique combined serial number using aprivate key of a public/private key pair; an imprinting device, whereinthe imprinting device is configured to imprint the digital signature onthe security instrument medium of the given security instrument; and adecoding device comprising: a second processor; and a second computerreadable storage medium having second computer readable program codeembodied in the second computer readable storage medium, wherein whenthe second computer readable program code is executed by the secondprocessor, the decoding device configured to: decode the digitalsignature marked onto the security instrument medium of the givensecurity instrument using a public key of the public/private key pair toobtain the combined serial number; compare the combined serial numberwith the unique watermark serial number incorporated within the securityinstrument medium of the given security instrument and the unique matterserial number marked onto the security instrument medium of the givensecurity instrument; and in response to determining that the uniquewatermark serial number incorporated within the security instrumentmedium of the security instrument and the unique matter serial numbermarked onto the security instrument medium of the given securityinstrument match the combined serial number, determine that the securityinstrument is authentic.
 4. The system of claim 3, wherein the secondcomputer readable program code is further configured to: in response todetermining that the unique watermark serial number incorporated withinthe security instrument medium of the given security instrument or theunique matter serial number marked onto the security instrument mediumof the given security instrument fails to match the decoded combinedserial number, determine that the security instrument is counterfeit.